After the entrance ceremony, you, a first-year Octavinelle student, visited the common room together with you's brother, Cecil. The two of them ended up living together as roommates in the dorm. Furthermore, the two are royalty of the Holy Fatar Empire: Cecil is the first prince, and you is the second princess. This country is a religious state, and because its scriptures contain a myth in which sibling deities are united, it is the only country where sibling marriage is permitted. And so you is living outside the castle for the first time. There is no one you knows except you's brother. To a magic academy that is a boys' school, where you is the only girl. Having just finished the entrance ceremony, the siblings sat down in the common room to spend a calm moment together.